THE ME RYES OF SENSATION. 
183 
induced upon the expansion of nervous matter, which is con- 
nected with the spot touched — an effect is propagated along the 
nerve that leads from that spot to the brain, and an impression or 
change is produced in the brain itself.” 
Common Sensation not so acute in the Quadruped as in the 
Biped. — The sensitive columns are small in the quadruped com- 
pared with the motor ones — they are small compared with the 
bulk of the animal, and the surface over which they are to be 
diffused. Animal power is needed for the purposes of their own 
existence, and in order to render them useful servants of man ; 
but a considerable portion of general sensibility would be a 
curse instead of a blessing. There are certain sensations con- 
nected with the support and the reproduction of life, which, 
probably, are as pleasurable to them as to the biped ; careful 
observation of the animal, and dissection of the nervous tissue 
of these parts, would lead to this conclusion : and, on the other 
hand, the nature of the integumental substance, and the super- 
added defence, in the form of hair and wool and feathers and 
scales, and the impossibility of contact with many an injurious 
object, shew that these animals were not destined to suffer ma- 
terially from many external agents : and, where the danger does 
not exist, nature seldom bestows the warning or the remedy. 
The skin being naturally protected from injury, has not that sen- 
sibility, one of whose offices, and not the least important one, is 
to put the animal on his guard. 
Reasons for this. — It is difficult to understand the indications 
of pain, and of the degree in which it exists, in the brute ; for 
the varying expression of the countenance and the faculty of 
speech are wanting : and there is also wanting, except where for 
certain purposes, and at certain times, instinct prompts it, a 
principle of mutual sympathy, and the power as well as the 
desire to be of mutual service. Therefore, while the human being 
permits his voice to tell and his features to express that which 
passes within, and, if the cause of his pain cannot always be 
removed, yet he experiences considerable relief from the commise- 
ration of his fellows, the inferior animal broods in silence over 
his misery, and the extent of that misery is disclosed only by 
the wasting of his frame, and the evident progress and ravages 
of disease. Cowardice, or the connexion of suffering with human 
agency, or the fear of and the natural desire to avoid a repetition 
of it, will frequently induce the animal, and especially the young 
one, to express the pain which he feels plainly and loudly enough; 
but it is seldom that he tells of that which he cannot connect 
with the agency or brutality of man, and oftener he seeks some 
lone retreat, where he either slowly pines away, or where Nature 
effects that restorative process which she oftener, and more ra- 
